Accelerated impact testing apparatus

ABSTRACT

Accelerated impact testing apparatus which simulates the dynamic strain in golf clubs, shafts and other specimens by rapidly transferring kinetic energy to the specimen from an instrumented tup that is free to rebound. The specimen is held in place by two holding fixtures uniquely designed to provide the appropriate boundary and support conditions for the transient strain to propagate in a manner similar to that of the actual application e.g. a golf club striking a ball. Force applied to the tup is generated by compressing a spring to a predetermined length and releasing its energy through a rapidly actuated latch. Actual force applied as a function of time is measured by a load cell located in the tup and the tup velocity just prior to impact is computed from a velocity sensor signal. Acceleration of the impact event is also recorded as well as strain levels in the shaft.

This application is a divisional of application Ser. No. 08,556,584,filed on Nov. 13, 1995 now U.S. Pat. No. 5,696,312.

BACKGROUND OF THE INVENTION

This invention relates to materials testing and pertains, morespecifically, to dynamic testing at various strain rates and loadingconditions and the controlling of velocity of an impactor and themaximum deflection of the specimen under test.

The increased demand for varied materials and manufacturing processeshas required that apparati be developed to meet the need for testingdevices which realistically simulate the dynamic strain environmentgenerated in various applications e.g. a golf shaft when striking aball, yet, are capable of evaluating a wide range of materials, and areeconomical and characterized by ease of use in the workplace.

The dynamic testing of materials has been carried out in the past byvarious impact apparati, however, to applicant's knowledge none employan improved cantilever type simple support configuration for thespecimen, and mode of operation as embodied in the present apparatus.There is need for such an improved support configuration which in usemore closely simulates actual strain and strain rates applied tomaterials during use in high strain and high strain rate applications.Furthermore, there is need for impact test apparatus and methods usefulfor the bending of tubular specimens. Strain and strain rates producedin tubular specimens tested by apparati using long cantilevered andrigidly fixed test specimens do not duplicate with sufficient validitythe dynamic strain environment generated in the actual applications.

SUMMARY OF THE INVENTION

It is a major object of the invention to provide accelerated impacttesting apparatus and method meeting the above need. Such apparatus istypically usable with respect to impact testing of a golf shaft havingfirst and second ends, and includes:

a) primary means to support the shaft intermediate the first and secondends,

b) secondary means to support the shaft near it second end and defininga downwardly curved support channel into which the second end of theshaft is downwardly displaceable in response to impact loading, and

c) a hammer located to be driven toward the shaft near its second end todeliver impact loading to the shaft.

Another object is to provide an anvil on the second end of the shaft tobe struck by the hammer (i.e. tup).

Yet another object is to provide a spring located to be compressed andto suddenly expand toward the hammer, and a latch to retain the hammeruntil expanding spring force is delivered to the hammer, and to releasethe hammer in response to such delivery.

An additional object includes provision of sensor means to sense thevelocity of hammer travel as it delivers such impact loading, and alsoto provide circuitry responsive to such velocity sensing to compute forexample the kinetic energy of the hammer at impact, or for velocityrecording.

Further objects include provision of apparatus that improves upondrop-tower type, as well as hydraulically and pneumatically associatedtype testers; apparatus for impact testing of specimens having a widevariety of configurations and over a large range of speeds, and toenable realistic and accurate data to be collected; provision ofapparatus for testing golf shaft durability without having to attach ahead to the shaft; provision of means to allow higher rates of testingof golf shafts, using a relatively small machine; provision of means toallow for realistic stress and stress rates to be applied to golf shaft,or other tubular specimens under test; provision of a support systemwhich allows stresses to be distributed in a specimen golf club shaftand in a realistic way so as to simulate a golf club striking a ball;and provision of means whereby the maximum strain applied to thespecimen is limited by adjustable bumper stops.

The invention will be understood more fully in the following detaileddescription of a preferred embodiment illustrated in the accompanyingdrawings, in which:

DRAWING DESCRIPTION

FIG. 1 is a front elevational view of accelerated impact testingapparatus embodying the invention;

FIG. 2 is a side elevational view, partially sectioned, of theaccelerated impact testing apparatus, taken on lines 2--2 of FIG. 1;

FIG. 3 is a partial top plan view of the accelerated impact testingapparatus, taken on lines 3--3 of FIG. 1;

FIG. 4 is a partial cross-sectional elevational view taken along lines4--4 of FIG. 3;

FIG. 5 is a partial cross-sectional elevational view of a bumper stopassembly taken along lines 5--5 of FIG. 4;

FIG. 6 is a partial cross-sectional elevational view of a front clamptaken along lines 6--6 of FIG. 4;

FIG. 7 is a cross-sectional elevational view of the front clamp takenalong lines 7--7 of FIG. 6;

FIG. 8 is an enlarged partial cross-sectional side view of the latchmechanism portion of the accelerated impact testing apparatus, seen inFIG. 1;

FIG. 9 is an enlarged cross-sectional plan view taken along lines 9--9of FIG. 8, and illustrating the top of a pressure plate and cross head;

FIG. 10 is an enlarged fragmentary side view of the apparatus, similarto FIG. 2, but with the components in another i.e. released operatingposition;

FIG. 11 is an enlarged elevational cross-sectional view of the tupassembly; and

FIG. 12 is a block diagram showing electrical system circuitry usable tocontrol the acceleration impact testing apparatus of FIGS. 1-11.

GENERAL ORGANIZATION

Referring first to FIGS. 1, 2, 8, and 10, the illustrated apparatus 100is usable to enable impact testing of a golf club shaft, seen at 101.The shaft has a first end 101a to support a hand grip (not shown) and asecond end 101b, to which a golf club head (not shown) is to beassembled. Typically, shaft end 101b is assembled into a supportingtubular hosel of a golf club head (see U.S. Pat. No. 5,163,682,incorporated herein by reference), and the hosel may be located withinthe head or externally thereof. The shaft end portion 101c adjacentportion 101b is typically located immediately above the hosel and is notdirectly supported by the hosel in use, whereby it is subjected to ahigh degree of shock. stress, i.e., bending stress, in response to highspeed impact of the golf club head with a golf ball. Also, shaft lowerend portion 101b is typically tubular and has reduced diameter ascompared with the larger diameter of the first end 101a.

It is, therefore, desirable to impact test such a shaft, as by sideimpacting second end portion or portions 101b and/or 101c, and as undershaft production conditions, to determine that a selected shaft issufficiently durable to withstand repeated use under ball strikingconditions, i.e., during play. The shaft may consist of graphite orcomposite material, as is known.

Basically, the apparatus shown comprises:

a) primary means to support the shaft 101 intermediate its first andsecond opposite ends (see for example clamp support at 44 on fixture35),

b) secondary means to support the shaft 101 near its second end anddefining a downwardly curved support channel into which the second endof the shaft is downwardly displaceable in response to impact loading(see for example holding bracket 43 on holding fixture 34; and U-shapedcross-section channel 130 curved downwardly in FIG. 10 to receive thesidewardly downwardly deflected shaft end portion 101c),

c) and a hammer or tup located to be driven downwardly toward the shaftnear its second end to deliver shaft bending impact loading to theshaft. (See for example tup 19 carried as by cross-head 17 in FIG. 10).

Accordingly, if the end portion of the sample shaft that is deflectedinto and along the U-shaped channel 130 does not fracture, it isdetermined that such sample shaft is acceptable, and that otherproduction shafts, on a production line from which the sample wasselected, are also acceptable. Downwardly curved channel 130 simulatesthe curvature of shaft bending above the hosel when golf club headstrikes a golf ball at high speed.

Note also, the provision of an anvil sleeve 33 fitted on the end portionof the shaft 101 to receive tup impact loading; the spring 15 to becompressed and to suddenly expand toward the hammer or tup to drive thelatter downwardly, and latch 18 that suddenly releases the spring andcrosshead 17.

DETAILED DESCRIPTION

Referring now to FIGS. 1, 2, 8 and 10, a frame plate indicated at 1 iscarried by and secured to two base members 1a which in turn incorporateleveling feet 3, at opposite ends of base member 2. Vertical member 4 ofthe apparatus is attached to frame 1 and provides an attaching surface4a for a top horizontal frame plate 6 and horizontal frame mid plate 8.Mid plate 8 and top plate 6 are attached together at their outermostends as by support rods 9.

A motor 5 is carried at the topmost surface of drive assembly 22 whichhas secure attachment to top plate 6. Torque from motor 5 is transmittedthrough a flexible coupling 14 to vertical ball screw 13. The verticalalignment of ball screw 13 is maintained by two pillow block bearings 23that are contained in pillow block bearing housing 24. Bearings 23 areattached to the rear surface of drive assembly 22.

As shown in FIGS. 1 and 2, a nut 110 passes the screw, and is threadablyengaged therewith. The nut is carried by a horizontal crosshead 111.Opposite end portions 111a and 111b of the crosshead define verticalbores at 111a' and 111b' that slidably receive the vertical guide railsor rods 12. The latter have opposite ends attached to the frame at 113and to the plate 6 at 114.

Compression spring 15 extending about the screw has its upper end 15abearing against the lower end of the nut 110, and its lower end 15bengages a pressure plate 16, as seen in FIG. 1. That plate is carried bya crosshead 17 having opposite end portions 17a and 17b that definebores 17a' and 17b' receiving and guiding along the guide rails 12.Linear bearings may be provided at 17a' and 17b'. Connected to theunderside of the crosshead 17 is a tup assembly 45 (see FIG. 11) thatincludes downwardly convex tup 19, tup rod 19a, a housing 115 defining abore 116 passing rod 19a, a spring 47 in the housing 115, and a loadcell 117 in the housing between the upper rod 19a' of the rod 19a andthe lower side 17a of the crosshead 17. The housing has flanges 115aattached to the crosshead, as shown. Accordingly, as tup 19 impactsanvil sleeve 33 on the shaft 101 (see FIG. 10), reaction force istransmitted to the load cell, to produce impact force measurement. Notethe end portion 101d of shaft 101 being bent downwardly in FIG. 10,along U-cross section channel defined by synthetic resinous (for exampleDELRIN) channel lining 118. The downwardly convex surface of the tupaccommodates to the sleeve 33 as the latter is deflected downwardly.

Upward force resulting from spring 15 compression is taken by thrustbearing 25 contained in thrust bearing housing 26 attached to top plate6. Top plate 6 provides support to the upper ends of guide rails 12which pass through mid plate 8. The bottom ends of guide rails 12 areattached to frame 1, as referred to above.

Turning now to FIG. 2, angled support bars 27 are provided and aresecured to frame 1 and vertical member 4 to support vertical member 4and to provide a mounting surface for motor controller 28 and amplifier37. When spring compression assembly 11 is in its uppermost position asseen in FIG. 2, it activates upper limit switch 29 which in turnprovides a signal to disconnect electrical power transmission to motor5. Note flange 11a projecting sidewardly from nut 110, toward the limitswitch.

Test specimen shaft 101 is held in place by front holding fixture 34 andrear holding fixture 35 (see FIGS. 2 and 3). The test specimen is heldfrom moving during and after impact force is applied by restrainingbracket 43 and restraining clamp 44. Smooth, downward groove such aschannel at 130 is contoured onto front holding fixture 34 to establishthe boundary conditions for the test, including preventing the testspecimen end portions 101c and 101d from bending sideways, but allowingthem to bend downward. The channel also prevents sharp local bending.The groove of front holding fixture 34 and the bottom of restrainingbracket 43 are lined with durable synthetic resinous material such asDELRIN to ensure that no failures originate in the test specimen, due tosharp edges. Rear holding fixture 35 is spaced approximately eighteen(18) inches from the tup 10 strike point (as when a golf club shaft isunder test) to assure that no strain wave reflected from rear holdingfixture 35 arrives back at the strike point, during the impact eventincluding bending of the shaft. Restraining clamp 44 may containelastomer cushion 55 to further insure no localized damage is causedduring the test. Note upward curvature at 55' to allow local upwardbending or bowing of the shaft, between 43 and 44.

As best seen in FIG. 8 crosshead 17 is held in its uppermost position byrestraining levers 42 and latch lever 18. The L-shaped levers 18 havepivot connection at 132 to posts 8a on plate 8, and levers 42 have pivotconnection at 133 to brackets 134 attached to frame member 4. The hookends 18a of levers 18 project beneath the ends 42a of levers 42, as seenin FIG. 8. Ends 42a project directly beneath crosshead 17. Rotation ofball screw 13 driven by motor 5 is transformed into a linear motion byball nut 110 which is secured to spring compression assembly 11. Springcompression assembly 11 is restrained from rotating by the linearbearings at 17a' and 17b' riding on guide rails 12, as seen in FIG. 9.The lower end of screw 13 is centered in a cone-shaped recess 139 inplate 26. See FIG. 8. The bottom end of spring 15 is attached topressure plate 16 which distributes force to crosshead 17 (also see FIG.9). The crosshead may consist of lightweight metal such as aluminum toreduce its acceleration mass.

Referring to FIG. 12 operation of the accelerated impact test apparatusis controlled by computer 40 which executes a unique program developedfor example with LabVIEW software. Other software can be used. Thecomplete interface between computer 40 and the impact testing apparatusis make up of data acquisition card 39, interface/relay box 38 andsignal conditioner 48. The test sequence begins by activating motor 5which turns ball screw 13 and drives spring compression assembly 11downward thus compressing spring 15 and applying force to pressure plate16 and the restrained crosshead 17. The energy stored in spring 15 ispredetermined and established by the length of an adjustable latchtripping bolt 30 threadably connected to part 11a as shown. When latchtripping bolt 30 moves sufficiently downward, it engages and causeslatch lever 18 upper lateral extent 18c to rotate about its pivot axis132 (see FIG. 10), thereby removing under support from restraining lever42 which immediately rotates about its pivot axis at 133 to avoidfrictional forces, and allowing crosshead 17 to suddenly acceleratedownward under force applied by spring 15. The continued downward motionof projecting extent 18c of latch lever 18 causes it to strike lowerlimit switch 32, which in turn interrupts electrical power to motor 5.

As best seen in FIG. 10 and FIG. 4, downward impelled travelingcrosshead 17 with attached tup 19 strikes anvil sleeve 33 and impartsits kinetic energy to test specimen 20. The lowermost position of tup 19is controlled by adjustable bumper stops 21 (see FIGS. 4 and 5) andbumper pads 50 which limit the downward travel of crosshead 17. Theurethane pads 50 protect the crosshead from damage upon striking. Thedownward acceleration of crosshead 17 is measured by the output ofaccelerometer 53 carried by the crosshead 17, such output beingamplified by charge amplifier 54 and transmitted to signal conditioner48 for routing through interface/relay box 38 and data acquisition card39 for recording by computer 40. The force applied by tup 19 is measuredby the output of load cell 46 which is sent to signal conditioner 48 androuted through interface/relay box 38 and data acquisition card 39 forrecording by computer 40. Spring 47 mounted in tup assembly 45 providesa constant calibration load for load cell 46 (see FIG. 11). Strain intest specimen 20 is measured by the outputs of strain gauge(#1) at 51and strain gauge(#2) at 52 (see FIG. 10) which are sent to signalconditioner 48 and routed through interface/relay box 38 and dataacquisition card 39 for recording by computer 40. Gauges 51 and 52 areattached to upper and lower sides of the shaft 101, as shown, betweenshaft first and second supports at 43 and 44, respectively.

Just prior to tup 19 striking tip sleeve or anvil 33, sensor flag 41(see FIG. 4), attached to crosshead 17, interrupts the laser beam ofvelocity sensor 37. The laser emitter/receiver device is located about0.25 inches from the flag. The velocity sensor signal is amplified byamplifier 36 and sent to interface/relay box 38 and in turn to dataacquisition card 39. This information is used by computer 40 todetermine the velocity and kinetic energy of tup 19 just prior to impactwith test specimen 101. The output of amplifier 37 is also transmittedto interface/relay box 38 to reverse the polarity of the signalcontrolling motor 5 and to apply electrical power to motor 5 to reverserotate screw 23 and return spring compression assembly 11 to itsuppermost position. Velocity sensor 37 is supplied with direct currentby power supply 49.

It is to be understood that the above detailed description of apreferred embodiment of the invention is provided by way of exampleonly. Many details of design and construction may be modified withoutdeparting from the true spirit and scope of the invention, as set forthin the appended claims.

We claim:
 1. An accelerated impact testing apparatus for simulatingactual strains and strain rates and measuring the strain and strain ratecharacteristics of materials using a falling impactor to impact aspecimen, and comprising:a) a crosshead, and acceleration means forapplying a predetermined force to the crosshead, b) impactor meanscarried by the crosshead for striking the specimen while the impactor istraveling, c) specimen holding means, d) latching means for holding theimpactor means in a first position while the acceleration means exertsinitial loading transmitted to the crosshead, e) velocity measuringmeans to detect and record impactor velocity just prior to impacting thespecimen, f) power means for driving the acceleration means, g)restriction means to prevent the impactor means from deflecting thespecimen beyond a preset limit, h) control means for starting andstopping the power means, and for collecting and organizing acquireddata, and i) means to prevent undesired damage to the specimen duringimpact, j) said specimen holding means including two support fixturesspaced sufficiently apart so that when the specimen is impacted, arealistic stress corresponding to stress undergone by the specimen inactual use is propagated in the specimen.
 2. The invention of claim 1wherein the acceleration means includes a compression spring withsupporting means to allow sudden expansion of the spring.
 3. Theinvention of claim 2 including a spring loading transition plate betweenthe spring and the impactor means.
 4. The invention of claim 1 includingelongated guidance means, and wherein the crosshead travels verticallyon the guidance means, which aligns the crosshead relative to thespecimen, maintaining force application in a downward direction.
 5. Theinvention of claim 4 including a tup and load cell assembly attached tothe bottom side of the crosshead to provide a downwardly convex strikingsurface and to load the load cell in response to such striking.
 6. Theinvention of claim 1 wherein the velocity measuring means includes alaser emitter/receiver device and a flag which travels with thecrosshead into and out of registration with a beam emitted by the laserdevice.
 7. The invention of claim 6 wherein the laser beam is detectedby a sensor and is amplified to boost the signal to the computer which,upon receiving the signal, calculates the velocity from the time thatthe beam is interrupted by the flag which rides on the crosshead, andincluding said sensor and said computer.
 8. The invention of claim 1including two adjustable bumpers located to stop crosshead downwardtravel and thereby stop the deflection of the specimen at a prescribedlimit.
 9. The invention of claim 8 wherein the bumpers comprise plasticbumpers to protect the bottom of the crosshead and still allow for ashort deceleration time.
 10. An accelerated impact testing apparatus forsimulating actual strains and strain rates and measuring the strain andstrain rate characteristics of materials using a falling impactor toimpact a specimen, and comprising:a) crosshead, and acceleration meansfor applying a predetermined force to the crosshead, b) impactor meanscarried by the crosshead for striking the specimen while the impactor istraveling, c) specimen holding means for allowing load and straintransients to develop in the specimen when impacted by said impactormeans, d) latching means for holding the impactor means in a firstposition while the acceleration means exerts initial loading transmittedto the crosshead, e) velocity measuring means to detect and recordimpactor velocity just prior to impacting the specimen, f) power meansfor driving the acceleration means, g) restriction means to prevent theimpactor means from deflecting the specimen beyond a preset limit, h)control means for starting and stopping the power means, and forcollecting and organizing acquired data, and i) specimen protectionmeans to prevent undesired damage to the specimen during impact, j) theacceleration means including a compression spring with supporting meansto allow sudden expansion of the spring, k) there being a spring loadingtransition plate between the spring and the impactor means, l) andwherein the transition plate contains a cone shaped center forself-centering of the end of a spring compressing screw carried by thepower means.
 11. The invention of claim 1 wherein the power meansincludes a motor and a force translation means which provides a linearforce to compress the spring.
 12. An accelerated impact testingapparatus for simulating actual strains and strain rates and measuringthe strain and strain rate characteristics of materials using a fallingimpactor to impact a specimen, and comprising:a) a crosshead, andacceleration means for applying a predetermined force to the crosshead,b) imoactor means carried by the crosshead for striking the specimenwhile the impactor is traveling, c) specimen holding means, d) latchingmeans for holding the impactor means in a first position while theacceleration means exerts initial loading transmitted to the crosshead,e) velocity measuring means to detect and record impactor velocity justprior to impacting the specimen, f) power means for driving theacceleration means, g) restriction means to prevent the impactor meansfrom deflecting the specimen beyond a preset limit, h) control means forstarting and stopping the power means, and for collecting and organizingacquired data, and i) means to prevent undesired damage to the specimenduring impact, j) said power means including a motor and a forcetranslation means which provides a linear force to compress the spring,k) and including an assembly that includes a ball screw and a ball nut,and wherein the motor turns said ball screw through a flexible couplingwhich allows said ball nut travel linearly to compress the spring. 13.The invention of claim 12 wherein the acceleration means is attached tothe ball nut allowing no rotational movement of the spring relative tothe ball nut.
 14. An accelerated impact testing apparatus for simulatingactual strains and strain rates and measuring the strain and strain ratecharacteristics of materials using a falling impactor to impact aspecimen, and comprising:a) a crosshead, and acceleration means forapplying a predetermined force to the crosshead, b) impactor meanscarried by the crosshead for striking the specimen while the impactor istraveling, c) specimen holding means, d) latching means for holding theimpactor means in a first position while the acceleration means exertsinitial loading transmitted to the crosshead, e) velocity measuringmeans to detect and record impactor velocity just prior to impacting thespecimen, f) power means for driving the acceleration means, g)restriction means to prevent the impactor means from deflecting thespecimen beyond a preset limit, h) control means for starting andstopping the power means, and for collecting and organizing acquireddata, and i) means to prevent undesired damage to the specimen duringimpact, j) and including elongated guidance means, and wherein thecrosshead travels vertically on the guidance means, which aligns thecrosshead relative to the specimen, maintaining force application in adownward direction, k) and wherein the crosshead consists of lightweightmetal to reduce the acceleration mass of the crosshead.
 15. Anaccelerated impact testing apparatus for simulating actual strains andstrain rates and measuring the strain and strain rate characteristics ofmaterials using a falling impactor to impact a specimen, andcomprising:a) a crosshead, and acceleration means for applying apredetermined force to the crosshead, b) impactor means carried by thecrosshead for striking the specimen while the impactor is traveling, c)specimen holding means, d) latching means for holding the impactor meansin a first position while the acceleration means exerts initial loadingtransmitted to the crosshead, e) velocity measuring means to detect andrecord impactor velocity just prior to impacting the specimen, f) powermeans for driving the acceleration means, g) restriction means toprevent the impactor means from deflecting the specimen beyond a presetlimit, h) control means for starting and stopping the power means, andfor collecting and organizing acquired data, and i) means to preventundesired damage to the specimen during impact, j) and includingelongated guidance means, and wherein the crosshead travels verticallyon the guidance means, which aligns the crosshead relative to thespecimen, maintaining force application in a downward direction, k) andincluding a tup and load cell assembly attached to the bottom side ofthe crosshead to provide a downwardly convex striking surface and toload the cell in response to such striking, l) and wherein the tupassembly includes a spring that provides a constant, calibrated forceagainst a load cell.
 16. An accelerated impact testing apparatus forsimulating actual strains and strain rates and measuring the strain andstrain rate characteristics of materials using a falling impactor toimpact a specimen, and comprising:a) a crosshead, and acceleration meansfor applying a predetermined force to the crosshead, b) impactor meanscarried by the crosshead for striking the specimen while the impactor istraveling, c) specimen holding means, d) latching means for holding theimpactor means in a first position while the acceleration means exertsinitial loading transmitted to the crosshead, e) velocity measuringmeans to detect and record impactor velocity just prior to impacting thespecimen, f) power means for driving the acceleration means, g)restriction means to prevent the impactor means from deflecting thespecimen beyond a preset limit, h) control means for starting andstopping the power means, and for collecting and organizing acquireddata, and i) means to prevent undesired damage to the specimen duringimpact, j) said acceleration means including a compression spring withsupporting means to allow sudden expansion of the spring, k) and whereinthe latching means includes a latch lever which holds up the crossheadunder the loading of the spring and thereby allows the spring to store apre-determined amount of energy, and a rotating restraining lever whichis interposed between the latching lever and said crosshead, to minimizefriction against the crosshead, both levers being releasable by a latchtripping means.
 17. The invention of claim 16 wherein the latch leverhas hinge connection to a support to allow for minimal upward motion ofthe crosshead as it slides when the latch lever is displaced by a latchtripping means.
 18. The invention of claim 16 wherein the restraininglever comprises a hinged member that is held in an upward positionbetween the crosshead and the latch lever arm, and upon release of thelatch lever the restraining lever rotates away from the crosshead forminimizing abrasion on the crosshead.
 19. The invention of claim 18wherein the restraining lever is held in its lower position by a springloaded hook system which allows for free travel of the crosshead afterits release.
 20. An accelerated impact testing apparatus for simulatingactual strains and strain rates and measuring the strain and strain ratecharacteristics of materials using a falling impactor to impact aspecimen, and comprising:a) a crosshead, and acceleration means forapplying a predetermined force to the crosshead, b) impactor meanscarried by the crosshead for striking the specimen while the impactor istraveling, c) specimen holding means, d) latching means for holding theimpactor means in a first position while the acceleration means exertsinitial loading transmitted to the crosshead, e) velocity measuringmeans to detect and record impactor velocity just prior to impacting thespecimen, f) power means for driving the acceleration means, g)restriction means to prevent the impactor means from deflecting thespecimen beyond a preset limit, h) control means for starting andstopping the power means, and for collecting and organizing acquireddata, and i) means to prevent undesired damage to the specimen duringimpact, j) said power means includes a motor and a force translationmeans which provides a linear force to compress the spring, k) andincluding an assembly that includes a ball screw and a ball nut, andwherein the motor turns said ball screw through a flexible couplingwhich allows said ball nut travel linearly to compress the spring, l)and including a latch tripping means that comprises a bolt that travelswith the ball screw and ball nut assembly and pushes down latching meansto release the latching means and allow the crosshead to move downward.21. The invention of claim 20 wherein the latch tripping bolt has threadconnection to the ball screw and ball nut assembly to provide foradjustment of spring compression such that the crosshead can be shotwith varying speeds.
 22. The invention of claim 4 wherein the guidancemeans comprises two metallic rods which guide and allow the crosshead totravel downward in an accurate and repeatable manner.
 23. The inventionof claim 22 including linear ball bearings encased inside the crossheadto guide on said guidance means.
 24. An accelerated impact testingapparatus for simulating actual strains and strain rates and measuringthe strain and strain rate characteristics of materials using a fallingimpactor to impact a specimen, and comprising:a) a crosshead, andacceleration means for applying a predetermined force to the crosshead,b) impactor means carried by the crosshead for striking the specimenwhile the impactor is traveling, c) specimen holding means, d) latchingmeans for holding the impactor means in a first position while theacceleration means exerts initial loading transmitted to the crosshead,e) velocity measuring means to detect and record impactor velocity justprior to impacting the specimen, f) power means for driving theacceleration means, g) restriction means to prevent the impactor meansfrom deflecting the specimen beyond a preset limit, h) control means forstarting and stopping the power means, and for collecting and organizingacquired data, and i) means to prevent undesired damage to the specimenduring impact, j) said velocity measuring means includes a laseremitter/receiver device and a flag which travels with the crosshead intoand out of registration with a beam emitted by the laser device, k) andwherein the control means includes a relay system, limit switches andlogic circuitry to control the range of motion of the ball nut andspring and then uses the laser device to activate the load cell andstrain gauge data collection sequence following which the relay is againactivated to move the ball nut to its original up position.
 25. Anaccelerated impact testing apparatus for simulating actual strains andstrain rates and measuring the strain and strain rate characteristics ofmaterials using a falling impactor to impact a specimen, andcomprising:a) a crosshead, and acceleration means for applying apredetermined force to the crosshead, b) impactor means carried by thecrosshead for striking the specimen while the impactor is traveling, c)specimen holding means, d) latching means for holding the impactor meansin a first position while the acceleration means exerts initial loadingtransmitted to the crosshead, e) velocity measuring means to detect andrecord impactor velocity just prior to impacting the specimen, f) powermeans for driving the acceleration means, g) restriction means toprevent the impactor means from deflecting the specimen beyond a presetlimit, h) control means for starting and stopping the power means, andfor collecting and organizing acquired data, and i) means to preventundesired damage to the specimen during impact, j) and wherein thespecimen holding means includes two support fixtures spaced about 18inches apart so that when the specimen is impacted a realistic stresscorresponding to stress undergone by the specimen in actual use ispropagated in the specimen.
 26. The invention of claim 25 wherein onefixture includes a back clamp of cantilever type which does not allowspecimen translation or rotation, and a front clamp including a supportwith an arcuate channel cut therein to receive the bent end of thespecimen and reduce the stress concentration in the specimen at thelocation of the channel.
 27. An accelerated impact testing apparatus forsimulating actual strains and strain rates and measuring the strain andstrain rate characteristics of materials using a falling impactor toimpact a specimen, and comprising:a crosshead, and acceleration meansfor applying a predetermined force to the crosshead, b) impactor meanscarried by the crosshead for striking the specimen while the impactor istraveling, c) specimen holding means, d) latching means for holding theimpactor means in a first position while the acceleration means exertsinitial loading transmitted to the crosshead, e) velocity measuringmeans to detect and record impactor velocity just prior to impacting thespecimen, f) power means for driving the acceleration means, g)restriction means to prevent the impactor means from deflecting thespecimen beyond a preset limit, h) control means for starting andstopping the power means, and for collecting and organizing acquireddata, and i) means to prevent undesired damage to the specimen duringimpact, j) and wherein the specimen protection means comprises a steelsleeve which is received onto the tip of specimen to protect thespecimen from damage and to ensure that the bending of the specimen isdirectly downward.
 28. The invention of claim 27 including and supportmeans for said holding means.
 29. The invention of claim 28 wherein saidspecimen is a golf club shaft.
 30. The invention of claim 29 whereinsaid shaft consists of graphite.